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Phosphorylation of Vpr regulates HIV type 1 nuclear import and macrophage infection
Isabelle Agostini1, Serguei Popov, Tang Hao
1Picower Institute for Medical Research, Manhasset, New York 11030, USA.
Abstract:
Viral protein R (Vpr) of human immunodeficiency virus type 1 (HIV-1) is a small accessory protein that regulates nuclear import of the viral preintegration complex and facilitates infection of nondividing cells, such as macrophages. Studies demonstrated that a fraction of Vpr molecules is phosphorylated in the virions and in HIV-1-infected cells, but the role of phosphorylation in nuclear import activity of Vpr has not been established. We found that Vpr is phosphorylated predominantly on the serine residue in position 79, and mutations affecting Vpr phosphorylation significantly attenuated viral replication in macrophages, but not in activated T lymphocytes or cell lines. The replication defect was mapped by polymerase chain reaction analysis to the step of nuclear import. These results suggest that phosphorylation of Vpr regulates its activity in the nuclear import of the HIV-1 preintegration complex.
Insights
Phosphorylation of human immunodeficiency virus type 1
Area of Science:
- Virology
- Molecular Biology
- Cell Biology
Background:
- Human immunodeficiency virus type 1 (HIV-1) utilizes Viral protein R (Vpr) as an accessory protein.
- Vpr is crucial for nuclear import of the viral preintegration complex and infects non-dividing cells like macrophages.
- The role of Vpr phosphorylation in its nuclear import function remains unclear.
Purpose of the Study:
- To investigate the role of Vpr phosphorylation in HIV-1 nuclear import and viral replication.
- To identify the specific site of Vpr phosphorylation and its functional consequences.
Main Methods:
- Site-directed mutagenesis to alter Vpr phosphorylation.
- Analysis of viral replication in macrophages, T lymphocytes, and cell lines.
- Polymerase chain reaction (PCR) to map replication defects to nuclear import.
Main Results:
- Vpr is predominantly phosphorylated at serine residue 79.
- Mutations affecting Vpr phosphorylation significantly reduced viral replication in macrophages.
- Replication defects were specifically linked to the nuclear import step.
Conclusions:
- Phosphorylation of Vpr at serine 79 is critical for its function in HIV-1 nuclear import.
- This phosphorylation event regulates the efficiency of viral preintegration complex nuclear import, particularly in macrophages.
- Targeting Vpr phosphorylation may offer a strategy to inhibit HIV-1 replication in specific cell types.